During recent years, increasing interest has been given to the use of iodine as an antiseptic or germicide because of the discovery that iodine can be complexed and solubilized by many substances. Iodine complexes allow iodine to be released slowly to provide persistent germicidal properties without allowing the iodine concentration to become high enough to cause side effects such as skin irritation. Illustrative of the prior art in this field are the following U.S. Pats.:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 2,710,277 Shelanski et al June 7, 1955 3,061,506 Nunn et al October 30, 1962 3,326,806 Dolby June 20, 1967 ______________________________________
One class of phoshate esters known to be useful as iodine complexing agents can be prepared by reacting P.sub.2 O.sub.5 or its equivalent with condensation products of ethylene oxide and monohydric alcohols wherein the alcohols may contain from 6-24 carbon atoms and the number of moles of ethylene oxide in the condensation products can vary widely. Phosphate esters of this type, particularly those containing from 10-20 moles of ethylene oxide per mole of alcohol, are disclosed in the prior art as effective iodine carriers or complexing agents. However, such complexes have a tendency to produce intolerable amounts of foam for some uses. The foam produced has a tendency to be slow-draining. Thus while sanitizers of this type are very good for cleaning bottles and the like, beads of foam often remain in the container which makes it difficult to tell if the bottles are clean. Since it is difficult to tell if only foam is left or if other impurities are present, this is especially troublesome in automated or continuous, fast-moving line (production-line type) operations where the foam must drain cleanly from the bottles in the few seconds between sanitizing and filling. Moreover, phosphate esters of this general type form unstable complexes with iodine when the ethylene oxide/alcohol mole ratio is reduced much below 10 (e.g., reduced to 3:1).
The germicidal properties of iodine are reported to vary with pH, optimum germicidal activity occurring under strongly acidic conditions.